Abstract
Test-time adaptation is a task that a pre-trained source model is updated during inference with given test data from target domains with different distributions. However, frequent updates in a long time without resetting the model will bring two main problems, i.e., error accumulation and catastrophic forgetting. Although some recent methods have alleviated the problems by designing new loss functions or update strategies, they are still very fragile to hyperparameters or suffer from storage burden. Besides, most methods treat each target domain equally, neglecting the characteristics of each target domain and the situation of the current model, which will mislead the update direction of the model. To address the above issues, we first leverage the mean cosine similarity per test batch between the features output by the source and updated models to measure the change of target domains. Then we summarize the elasticity of the mean cosine similarity to guide the model to update and restore adaptively. Motivated by this, we propose a frustratingly simple yet efficient method called Elastic-Test-time ENTropy Minimization (E-TENT) to dynamically adjust the mean cosine similarity based on the built relationship between it and the momentum coefficient. Combined with the extra three minimal improvements, E-TENT exhibits significant performance gains and strong robustness on CIFAR10-C, CIFAR100-C and ImageNet-C along with various practical scenarios.










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The datasets are all available online for public. CIFAR10-C: https://zenodo.org/records/2535967#.ZBiI7NDMKUk CIFAR100-C: https://zenodo.org/records/3555552#.ZBiJA9DMKUk ImageNet-C: https://zenodo.org/records/2235448#.Yj2RO_co_mF
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Acknowledgements
This work was supported in part by the National Key Research and Development Program of China under Grant 2022YFB3304602, Beijing Natural Science Foundation under Grant L243009, the National Nature Science Foundation of China under Grant 62473367 and the Science and Technology Service Network Initiative (STS) Project of Chinese Academy of Sciences under Grant STS-HP-202308.
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Conceptualization and methodology: JL. Formal analysis: JL and XB. Software: JL, JC and YW. Writing—original draft preparation: JL. Writing—review and editing: All authors. Funding acquisition: CL and JT. Supervision: All authors.
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Li, J., Liu, C., Bai, X. et al. Compression and restoration: exploring elasticity in continual test-time adaptation. Mach Learn 114, 104 (2025). https://doi.org/10.1007/s10994-025-06739-8
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DOI: https://doi.org/10.1007/s10994-025-06739-8